1. Technical Field
The present invention relates to mobile networks including end-to-end quality of service (QoS) management, and more particularly, relates to dynamic media authorization and management of QoS classes of a session (connection between users or mobile terminals, or between a mobile terminal and a server) comprising a plurality of different types of media streams within mobile networks.
2. Related Art
Modern mobile networks such as those networks standardized by 3GPP (3rd Generation Partnership Project) specifications including all GSM (Global System for Mobile Communications) and 3rd generations of GSM networks, are seamless integration of digital cellular networks and personal communications systems to provide telecommunication services including, for example, mobile data network services and IP multimedia services.
Each 3GPP system may include a core network and a radio access network infrastructure using General Packet Radio Service (GPRS) and Enhanced Data Rates for Global Evolution (EDGE) technologies or supporting Universal Terrestrial Radio Access (UTRA) operable in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD). The core network (CN) may be logically divided into circuit switched (CS) and packet switched (PS) domains with CN entities provided for user traffic and related signaling, and an IP Multimedia Subsystem (IMS) with core network (CN) entities provided for IP multimedia services. Some CN entities such as Home Subscriber Server (HSS), Home Location Register (HLR), Authentication Center (AuC), Visitor Location Register (VLR), and Equipment Identify Register (EIR) may be common to the PS and CS domains, while other CN entities such as Mobile Switching Center (MSC) and Gateway MSC are specific to the CS domain to handle circuit switched services to/from mobile stations, and Gateway GPRS (general packet radio service) Support Node (GGSN) and Serving GSN (SGSN) are specific to the PS domain to handle the packet transmission to/from the mobile stations.
For IP multimedia services, functional IMS entities, such as Call Session Control Function (CSCF), may be provided to handle CSCF related procedures, including establishing PDP (Packet Data Protocol, e.g., IP) context for IMS related signaling, registration and other procedures for IMS sessions. CSCF can act as Proxy CSCF (P-CSCF) to serve as a first contact point for a user equipment (UE) (i.e., device allowing a user to access to network services, such as, a mobile terminal) within the IP multimedia subsystem (IMS), Serving CSCF (S-CSCF) to handle session states in the network, or an Interrogating CSCF (I-CSCF) to serve as a contact point within an operator's network for all IMS connections destined to either a subscriber of that network operator or a roaming subscriber in a given service area. See, 3GPP Technical Specification (TS) 23.002, V5.9.0 (December 2002) “Network Architecture”; 3GPP TS 23.101, V4.0.0 (April 2002) “General UMTS Architecture”; and 3GPP TS 23.110, V4.0.0 (April 2001) “UMTS Access Stratum: Services and Functions”; and 3GPP Technical Specification (TS) 23.228, V6.0.1 (January 2003) “IP Multimedia Subsystem (IMS)”. All 3GPP (GSM/3G) specifications can be found and downloaded from the 3GPP server under ftp://ftp.3gpp.org/specs, and are hereby incorporated by reference herein. In addition, mechanisms for creating, maintaining and updating 3GPP specifications (including different Releases of a given 3GPP specification with new or changed functionality) can also be found in 3GPP Technical Specification (TS) 21.900 V5.0.1 (September 2002) “Technical Specification Group Working Methods.”
A Policy Decision Function (PDF) has been standardized to supervise the management of quality of service (QoS) classes of a session comprising a plurality of media streams, make policy decisions based on the session and media related information, including the maximum authorized traffic class for a given media flow between two users (mobile terminals), or between a mobile terminal and a server, and then exchange decision information with the GGSN via a Go interface, as set forth in the 3GPP TS 29.207 V.5.2.0 (December 2002) “Policy Control over Go Interface”, Release 5; 3GPP TS 23.207 V.5.6.0 (December 2002) “End-To-End Quality of Service (QoS) Concept and Architecture”, Release 5; and 3GPP TS 29.208 V.5.2.0 (December 2002) “End-To-End Quality of Service (QoS) signaling flows”, Release 5. Such PDF may be integrated into the P-CSCF as set forth in the 3GPP Specification, Release 5 (December 2002), or alternatively, may be implemented in a separate network element that is separate from the P-CSCF as set forth in the 3GPP Specification, Release 6 (January 2003).
In general, when a session (connection) is established between user equipments (UEs) (e.g., mobile terminals), or between a mobile terminal and a server, and the session is modified (e.g. from bi-directional audio and unidirectional video to unidirectional video only), the traffic class is changed by the PDF (from conversational to streaming). This is because the session as established between user equipments (UEs) (e.g., mobile terminals), or between a mobile terminal and a server, comprises a bidirectional audio flow and a unidirectional video flow. The bi-directional audio flow is used for a real-time conversation and, consequently, requires a low delay real-time traffic class, i.e., the CONVERSATIONAL traffic class. The unidirectional video flow is used for transferring moving video pictures in one direction only. Such a unidirectional real-time video flow tolerates longer transmission delays and delay variations (a.k.a., jitter) because the sender does not expect to receive any responses. As a result, the unidirectional real-time flow typically uses a STREAMING traffic class in practice. If the session is modified, that is, if one of the bidirectional audio flow and the unidirectional video flow is terminated and removed from the session, the traffic class for bearer resources of the session needs to be changed by the PDF accordingly. For example, if the bidirectional audio flow with the CONVERSIONAL traffic class is removed from the session, the unidirectional video flow, with the STREAMING traffic class as a requirement by default, now has the “highest traffic class” of the session. Consequently, the PDF changes (i.e., downgrade) the traffic class for the bearer of the session from CONVERSATIONAL traffic class to STREAMING traffic class.
However, some parameters, such as buffer size in the receiving terminal are different in these traffic classes, the change of the traffic class with the inherent change of the transmission delay will cause buffer underflows at the receiving terminal or server, thereby reducing the quality of the connection perceived by the end user.
Another significant problem may occur, when a unidirectional (e.g. video) stream is added to an existing session comprising a bidirectional (e.g. audio) stream. The signalled traffic class request of the unidirectional video stream is typically streaming. The traffic class of the bidirectional session is conversational. If the media streams have a temporal relationship (e.g. verbal explanation of the video stream in the audio stream), the difference of the traffic classes will cause a difference in the transmission delays (due to different buffer lengths at the receivers to compensate the different delays and delay jitters in the transmission), thereby reducing the quality of the connection perceived by the end user.
Accordingly, there is a need for solutions that can be applicable to all systems in which one session (connection between users or mobile terminals, or between a mobile terminal and a server) may comprise a plurality of different types of media streams and that relate to dynamic media authorization and better management of quality of service (QoS) classes of a session (connection between users or mobile terminals, or between a mobile terminal and a server) comprising a plurality of different types of media streams within mobile networks such that, when media stream(s) are modified (new ones started and existing ones deleted) during the session, the traffic class of a session is defined by the highest traffic class requirement by the media flows belonging to the same session in order to eliminate the difference of transmission delays of media streams belonging to the same session and, therefore, improving the quality of the connection perceived by the end user.